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LDC1000EVM: Sensor frequency and sensor capacitor selection using LDCCOILEVM coils.

Andrea Comina
Prodigy 20 points
Part Number: LDC1000EVM
Other Parts Discussed in Thread: LDCCOILEVM, LDC1101

I am using the coils provided by LDCCOILEVM with the LDC1000EVM.

How to properly set up sensor frequency and C for each one of this coils?

I know that I have to use this formula:  .

I know that f_sensor has to be between 5kHz and 5MHz.

1) How to choose the value of L for each coil of LDCCOILEVM from the datasheet?

2) Should I have to see this value of L when no target is close to the coil?

3) Which one between f_sensor and C have I to choose in order to determine the other?

  • 0
    TI__Genius 14270 points
    Hello Andrea,

    Unless you must work in the frequency range of 5KHz to 500KHz, I strongly recommend using the LDC1101 instead of the LDC1000, as it is superior and also cheaper.

    OK, to answer your questions.
    1) Use the L value from the EVMCOIL guide corresponding to ~100kHz; this value is acceptable to use up to 80% of the self resonant frequency (SRF)of the sensor. You should not set the sensor frequency >80% for SRF.

    2) You need to make sure that the sensor frequency is within the specified operating region across all ranges of target movement that can happen in your system.

    3) Generally, set the sensor frequency higher in the device range if possible, but try not to let the sensor capacitor become too small (<50pF, although some systems may require much higher values of sensor capacitance).

    If you are using the LDC1000, make sure you set the CFB capacitor as instructed in the section 8.1.3 of the datasheet.

    Regards.

    ChrisO